Rudder Play

[kb79]

The last time I dove our boat, I noticed that there's about an 1/8" of play on either side laterally when I push on the rudder.

Is this a lot? I remember the surveyor manipulating the rudder during the haul out survey and telling me that there was minimal play which was good. Is 1/8" minimal or should there be no play at all?

How sloppy is sloppy?

I've got a CS 36 with a partial skeg.

[Charlie]

No play is best but I have sailed on some Santana 22's on the bay where there was 1/2 " or more of play. I would guess it is not emergent but would be good to take off the rudder and redo the bearings at some point.

[kb79]

We're in New Zealand now and are planning a second season in the western South Pacific. I don't have a reason to haul out otherwise... think it merits a haul out for this problem alone? Any suggestions on what I can do with the boat in the water to asses the magnitude of the problem?

[colemj]

Depends on where the play is. If the rudder shaft is moving around in the bearing, I would not be too worried about 1/8" of play - you have a long time left on it and are in no danger. If the rudder is moving on the shaft, I would haul out immediately and get that fixed.

Mark

[Charlie]

Originally Posted by kb79

We're in New Zealand now and are planning a second season in the western South Pacific. I don't have a reason to haul out otherwise... think it merits a haul out for this problem alone? Any suggestions on what I can do with the boat in the water to asses the magnitude of the problem?

I would lash the helm over to one side and then see if the rudder moves at all. If the rudder is moving with the helm lashed over it may be coming loose from the rudder post which is of way more concern then a loose bearing. Can you see the bearings from the top of the boat or inside the lazaret. Given the extents of your travel I would err of the side of caution.

[Bash]

Originally Posted by kb79

We're in New Zealand now and are planning a second season in the western South Pacific. I don't have a reason to haul out otherwise... think it merits a haul out for this problem alone? Any suggestions on what I can do with the boat in the water to asses the magnitude of the problem?

I'm not sure you've got a problem. On a rack-and-pinion system, 1/8" of play could be worrisome. On cable systems, 1/8" of play might seem entirely tight.

Worry less about how it feels when you're diving on the rudder, and more about how it feels when you're at the helm with the rail down. If you don't feel the play at that point, I doubt it should concern you other than to track it as the system ages.

Regardless, check all points of the linkage, especially the quadrant. If the play comes from loose bolts, tighten them up. If the quadrant moves when the shaft doesn't you've got problems.

[rognvald]

KB, the most obvious problem (from your description) is worn rudder bearings. There is usually one at the top and one at the bottom of the rudder shaft. A small amount of play is acceptable in protected waters, but if you're sailing offshore, it will only get worse. Drop the rudder, inspect and replace the bearing(s) as needed. Good luck and good sailing, Ron

[4HMainer]

Play in bearings very much depends on the size of shaft.

In mm you have 3.175mm RD

But as a guess if we assume a 50mm diameter shaft then a new bearing would have 0.20mm play or Radial Displacement (RD). On this size of bearing it is advised that the bearing should be changed when the RD reaches or approaches 1.25mm.

For a 4" 100.00mm shaft the clearance is only slightly larger 0.34 when new and 2.50 you should change.

At greater clearances the bearing surface area reduces considerably and wear rates also ramp up.

These are figures for Maritex Aquarius other materials will differ so check with the manufacturer or supplier.